With the continuous development of information technologies, an interaction mode between a mobile network operator and a third party service provider increasingly tends to be an XML (Extensible Markup Language) mechanism: An anchor entity in a network and a third party application function establish an HTTP (Hypertext Transfer Protocol) connection, and the anchor entity and another entity in a network (that is, a destination entity, with which the third party application function requests to establish a session, in a network) establish a Diameter (where the Diameter protocol is an upgrade version of the RADIUS protocol) session. In this case, the anchor entity is used as an agent to perform addressing for the third party application function, so as to enable the third party application function to access an operator network, to implement interaction between the third party application function and the destination entity in the network. The anchor entity may be understood as a network edge device that is in a mobile network and can directly communicate with an out-of-network device (for example, the third party application function). Referring to a schematic diagram shown in FIG. 1, a Protocol Converter PCin the figure is used as an anchor entity to establish an HTTP connection to a third party application function AF, and establish a Diameter session with a destination entity PCRF (Policy and Charging Rules Function) in a network with which the application function expects to establish a session.
If in a process of establishing a session between the third party application function and the destination entity in the network, a case in which multiple application functions address a same PCRF by using a same Protocol Converter occurs, the Protocol Converter cannot determine that a flow in a session between the Protocol Converter and the PCRF is corresponding to which application function, thereby causing a problem that a packet flow flowing through the Protocol Converter cannot be accurately forwarded to a destination application function.